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    <title>Document</title>
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<body>
    <script>
        console.log(10 > 20); //false
        console.log(20 >= 5); //true
        var n1 = 20;
        var n2 = 30;
        console.log(n1 < n2); //true
        console.log(n1 <= n2); //true
        // 判断相等 只是判断值相等
        console.log(n1 == n2); //false
        console.log(10 == "10"); //数据类型不一致 判断时会自动转换类型 10 与字符串的是10 是相等
        console.log(undefined == undefined); //true
        console.log(null == null); //true
        console.log(null == undefined); //true
        console.log(NaN == NaN); //false
        // != 判断不相等
        console.log(10 != 20); //true
        console.log(10 != 10); //false

        // === 全等判断 要求 值与数据类型全部相同 才为真
        console.log(10 === "10");//false
        // !== 判断不全等 只要只与数据类型中有一个不相同就得到true
        console.log(10 !== "10");//true
        
    </script>
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